Printing telegraph system



1.x l v 1ff`.5egpt 26, 1933- A. W. BREYFOGEL PRINTING TELEGRAPH SYSTEMOriginal Filed Dec.

In. W .MJ N.

@Mw f wh Q EL r EL WT M.. CQ

gwen/Coz atented Sept. 26, 1933l PRINTING TELEGRAPH SYSTEM Albert W.Breyfogel, Brooklyn, N. Y., assignor to The Western Union TelegraphCompany, New York, N. Y., a corporation of New York Application December30, 1930, Serial No. 505,609

Renewed December 3, 1932 The relay circuit may be described in more de-This invention relates to a printing telegraph system, and in particularto a telegraph system in which thyratron or other grid-controlled,gaslled thermionic tubes are employed as relays for operating themagnets of telegraph printers in accordance with incoming signals.

An object of my invention is to devise a gridcontrolled, gas-filled tubesystem for telegraph printers in which there are no stabilizingbatteries, and in which the necessary operating potentials are supplieddirectly from potential drops across resistances connected inthe platecircuit of the amplier controlling these grid-controlled, gas-filledtubes.

Another object of my invention is to devise such a relay circuit inwhich the grid elements of the tubes are maintained at definitepotentials with respect to the cathode elements at all times and arenever left free or floating.

A further object of my invention is to devise a grid-controlled,gas-lled tube circuit for the operation of one or more telegraphprinters in which upon the receipt of successive positive signalimpulses the magnets of two printers are operated alternately, andduring no signal impulse periods the magnets of only one printerareoperated depending upon which printer was last operated by positiveimpulses, and negative sig- Vnal impulses are ineffective to operateeither printer.

This invention is an improvement upon the relay circuit disclosed inFigure 2 of the copending application of H. H. Haglund, Serial No.343,109.

My invention is illustrated in the accompanying drawing in which:

Figure 1 is a circuit diagram of the novel relay circuit of thisinvention; and

Figure 2 is a curve representing current variations in the plate circuitof the amplifier controlling the thyratron relays.

Referring to Figure 1, the general arrangement of the inventioncomprises a vacuum tube relay VT1 having its input connected to anincoming line L, and its output circuit controlling the input circuitsof two relays T1 and T2. Relay T1 controls the -printer magnets ofprinter A through circuits completed by brushes BR1 associated withpick-up rings R1 and R2, and by brushes BRz associated with plate ringsR3 and R4. Relay T2 controls the magnets of printer B through circuitscompleted by brushes BB1 associated with pick-up rings R1 and R2, and bylrushes BRa associated with plate rings R5 and tail as follows:

In the power or outputstage of the vacuum tube amplier VT1 is a networkof resistances r1, 1'2, r3, r4, 1'5 and rs. These resistances are protothe grid G1 of tube T1 and to the (a) segments ofpick-up ring R1. PointE is connected to the grid G2 of tube T2 and to the (b) segments ofpick-up ring R1. The plate P1 of tube T1 is connected to the solid platering R3 and the plate P2 of tube T2 is connected to the solid plate ringR5. The segments of plate rings R4 and Re are connected through theselecting magnets of the A and B printers to plus battery Bz as shown.The negative side of the battery is connected to the point A.

In order that the'operation of the circuit may be made perfectly clear,it might be well to assume certain resistance and circuit values in someof the circuits. Assume the resistances r1, r2, 'n and T5 to be 200 ohmseach, r3 and rs to be 2000 ohms each and 17 equal to '7.5 ohms. Let itfurther be assume that for a given anode potential the thyratron tubesT1 and T2 will not start when the voltage on the grid is minus 4.5 voltsor more with respect to the cathode but that they will start when thevoltage on the grid is minus 4 Volts or less with respect tothe'cathode. This voltage is very well denedfor thyratron tubes with agiven anode potential., l

Let it also be assumed that the current in the power or output stage ofthe vacuum tube amplifier VT1, varies between 25 and 55 milliamperes asshown in Fig. 2. When the polarity -of ther incoming signal is plus, thecurrent is 25 milliamperes; when the signal is zero, the current is 4,0milliamperes; and when the signal is minus the current is 55milliamperes.

Suppose the polarity of the incoming signal is plus and the current inthe plate circuit of the vacuum tube amplifier is 25 milliamperes. Thiscurrent will divide equally between the two branches of the resistancenetwork, 12.5 milliamperes flowing through the resistances r4, f5 andrs. These currents produce a potential drop of 2.5 volts across each ofthe resistances r1 and r2 and r4 and rs. The potential at the point Awill to the potential at the points C and E. Also the potential at thegrids of'the two tubes T1 and T2 is minus 5 volts with respect to thepoint A and the cathodes since the grids of the two tubes T1 and T2 areconnected respectively to the points C and E. This voltage is sufcientlyhigh to prevent either of the tubes T1 and T2 from starting according tothe previous suppositions. The pickup brushes BR1 now make contact withthe 1al segments of rings R1 and R2, and the plate brushes BRz makecontact with the 1a segments of rings R3 and R1. Plus battery is placedon the plate P1 of tube T1 through ring R3, brushes BR2, segment 1a ofring R4, and No. 1 selecting magnet of the A printer. The brushes BR1momentarily short-circuitk the resistance r2 thus causing the potentialat the grid G1 of tube T1 to be reduced from 5 to 3.5 volts and tube T1starts. Now 200 mlliamperes of current flows from plus battery throughNo. 1 selecting magnet of the A printer, through segment 1d of ring R4,brushes BR2, ring Rs, through plate P1 to cathode of tube T1, throughresistance Rv to minus battery. No. 1 selecting magnet of the A printeris operated, and the 200 mlliamperes owing in this circuit produces avoltage drop of 1.5 volts across the resistance r2. This voltage drop,is in the same d1- rection as the voltage drop across the resistance r1and raises the voltage at the point B to minus 4 volts with respect tothe cathode.

The pick-up brushes vBR1 now pass onto the 1b segments of rings R1 andR2, and the brushes BRa pass onto the 1t segments of ring Re. Thebrushes BR1 short-circuit the resistance rs causing the voltage at thegrid G2 of tube T2 to fall from 6.5 volts to -4 volts and tube T2starts. Current will now flow from plus battery through No. 1 selectingmagnet of the B printer, through segment 1b of ring Re, brushes BRa,ring Rs, through the plate P1 to cathode of tube T2, through resistancef7 to minus battery. No. 1 selecting magnet of the B'printer will beoperated, and 400 mlliamperes will flow through the resistance r1,producing a voltage drop of 3 volts, which adds to the voltage dropacross resistance r4 and raises the voltage at the point D to minus 5.5volts. But,

` as tube T2 has already been started, it cannot be again influenced bythe grid until the arc has been stopped by removing the anode potential.Tube T2 then continues to pass current.

The plate brushes BR2 now pass of! the seg-f ment 1a of ring R4,removing the anode potential from the plate P1 of tube T1, thus causingthe arc to stop and tube T1 ceases to function. This reduces the currentthrough resistance 17 to 200 mlliamperes and reduces the voltage dropacross this resistance r1 to-1.5 volts. As the brushes BR1 now pass ontothe 2a segments of rings R1 and R2, and the brushes BR2 pass onto the 2asegments of rings R3 and R4, the resistance r2 is again short-circuitedand the voltage at the grid G1 of tube T1 is reduced from 6.5 volts to-4 volts and tube T1 again starts.

This cycle of events will continue so long as the incoming signal isplus and the plate current of the vacuum tube VT1 is 25 mlliamperes, i.e. each tube T1 and T2 will start when the pickup brushes BR1 come incontact with the corresponding pick-up segments.

Suppose that the voltage of the incoming signal falls to zero asillustrated in Fig. 2 and that the current in the plate circuit of thevacuum tube VT1 rises to 40 mlliamperes. A150 .SUPPOSQ that the tube T2is operating and the brush BRa is still making contact with the platesegment 5b.

When the pick-up brushes BR1 move onto the 1a segments of rings R1 andR2, the resistance r2 is again short-circuited but the voltage lappliedto the grid G1 of tube T1 is now minus 5.5 volts with respect to thecathode and tube T1 does not start. When the current in the platecircuit of the tube VT1increased to 40 mlliamperes, the drop across theresistance r1 increased from 2.5 to 4 volts and since tube T2 is stilloperating, the voltage drop of 1.5 volts across the resistance 17 isaiding the voltage drop across the resistance r1 making the voltage onthe grid G1 of tube T1 minus 5.5 volts with respect to the cathode. Thebrushes BRs now pass oi the segment 511 of ring Re removing the anodepotential from the plate P2 of tube T2, thus causing the arc to stop andtube T2 ceases to function. The voltage drop across the resistance T1now, falls to zero. The pick-up brushes BR1 now move onto the 1bsegments of rings R1 and R2 and the plate brushes BR: move onto the 1bsegment of ring Re. The

resistance 15 is short-circuited by the brushes' BR1 thus causing thevoltage at the grid G2 oi tube T2 to fall from minus 8 to minus 4 volts,and tube T2 again starts.

This cycle of events will continue so long as the potential of theincoming signal remains zero and the plate current of the vacuum tubeVT1 is 40 mlliamperes. That is, the relay tube which was last operatedby a plus signal will alone continue to operate after the signal voltagehas fallen to zero. The other tube will never operate so long as thiscondition continues.

Now suppose the incoming signal becomes minus and the current in theplate circuit of the vacuum tube VT1 rises to 55 mlliamperes. Thisincrease in current will produce an increased voltage drop across theresistances r1, r2, r1 and rs. The voltage drop across each of theseresistances will be 5.5 volts. Also suppose that the tube T2 isoperating and the brush BRa is still making contact with the platesegment 511.

When the pick-up brushes BR1 move onto the la segments of rings R1 andR2, the resistance r2 is again short-circuited, and the voltage appliedto the grid G1 of tube T1 becomes minus 7 volts with respect to thecathode, and tube T1 cannot start. When the current in the plate circuitof the tube VT1 increases to 55 mlliamperes, the voltage drop acrossresistance r1 increased from 4 volts to 5.5 volts, and since the tube T2is still operating, the voltage drop of 1.5 volts across the resistancer1 is aiding the voltage drop across the resistance r1, making thevoltage on the grid G1 vof tube T1 minus 7 volts with respect to thecathode. The brushes BR: now pass oi the segment 5b removing the anodepotential from the plate P2 of tube T2 thus causing the arc to stop, andtube T2 ceases to function. The voltage drop across the resistance n nowfalls to zero. The pick-up brushes BR1 now move onto the 1b segments ofrings R1 and R2 and the plate brushes move onto the 1b segment of ringRe. The resistance f5 is short-circuited by the brushes BR1, thiscausing the voltage at the grid G2 of T2 to fall from minus 11 voltageto minus 5.5 volts. This voltage is above that necessary to permit thetube to start and tube T2, therefore, does not start.

This cycle of events will continue so long as the incoming signal isminus in polarity and the plate current of the tube VT1 is 55inilliamperes.

That is, neither relay tube is operated when the incoming signal isminus. n

From the foregoing it is seen that when the incoming signal is plus,each tube will start when the pick-up brushes BRi pass onto theirassociated pick-up segments, and when the incoming signal is minus,neither tube will start. Also, when the incoming signal falls to zero,one tube will start every time the pick-up segments associated with itare short-circuited by the pick-up 'brushes'BRL Which tube will startdepends upon the position of jthe brushes and whether the incomingsignal falls from plus to zero or rises from vminus to zero.

From the foregoing description of the operation of the circuit, it willbe seen that the grids of the two relay tubesv never go plus, and thatstarting of the tubes is accomplished by reducing the negative bias tosuch a negative value as will permit starting. This makes the relaytubes more stable for the reason that if the grid goes positive, itdraws current and in doing so builds up a charge whichchanges the gridpotential needed to make the tube start.

It will also be noticed that all biasing or stabif lizing batteries havebeen eliminated and that the grids of the relay tubes are kept'at theirproper f potentials by the voltage drops in the signaling circuititself. Furthermore, the grids of the two relay tubes are neverdisconnected from the signaling circuit and are never left free to beaiected by extraneous pick-up or disturbances.

I claim:

1. In a signaling system,- a signaling circuit, a grid-controlled,gas-filled tube having its input circuit connected to said signalingcircuit, means for normally maintaining the grid of said tube negativewith respect to its cathode, and additional means responsive to positivesignal impulses to reduce said negative biasing potential whilemaintaining its polarity the same. 2. In a signaling system, a signalingcircuit, a grid-controlled, gas-filled tube having its input circuitconnected to said signaling circuit, means 'for normally maintaining thegrid of said tube negative with respect to its cathode, and additionalmeans responsive to'negative signal impulses to increase said negativepotential.

3. In a signaling system, a signaling circuit, a grid-controlled,gas-filled tube having its input circuit connected to said signalingcircuit, means "for normally maintaining the grid of said tube negativewith respect to its cathode, and means "operable in synchronism withincoming signals negative.

4. In a signaling system, a signaling circuit, a grid-controlled,gas-filled tube having its input circuit connected to said signalingcircuit, means for normally maintaining the grid of said tube y negativewth respect to its cathode, and means responsive to signal impulses todecrease said negative biasing potential for positive signals andincrease said potential for negative signals while maintaining thepolarity unchanged, and means operable in synchronism with said impulsesfor further reducing said negative biasing potential during positive andno signal periods.

5. In a signaling system, a signaling circuit including a resistance, agrid-controlled, gas-lled tube having its input circuit connected acrosssaid resistance, means for establishing a direct current through saidresistance to normally 6. In a signaling system, a signaling circuit in-4cluding a resistance, a grid-controlled, gaslled tube having its inputcircuit connected across said resistance, means for establishing adirect current through said resistance to normally maintain the grid ofsaid tube negative with respect to its cathode, means for decreasingsaid biasing current upon the receipt of positive signals and increasingsaid biasing current upon receipt of negative signals, and meansoperable in synchronism with said signals for periodically reducing saidnegative biasing potential.

- 7. In a signaling system, a signaling circuit terminated with a vacuumtube amplier, a source of current and a resistance in the output stageof said amplifier, a grid-controlled, gas-lled tube having its inputcircuit connected across at least a portion of said resistance wherebythe plate current of said amplifier normally maintains the grid of saidgas-filled tube negative with respect to its cathode, said vacuum tubeamplifier being so connected to said signaling circuit that positivesignals produce a decrease in the current through said resistance, andnegative signals produce an increase in said current.

8. In a signaling system, a signaling circuit terminated with a vacuumtube amplifier, a source of current and a resistance in the output stageof said amplier, a grid-controlled, gas-lled tube having its inputcircuit connected across at least a portion of said resistance wherebythe plate current of said amplifier normally maintains the grid of saidgaselled tube negative with respect to its cathode, said vacuum tubeamplifier being so connected to said signaling circuit that positivesignals produce a decrease in the current through said resistance, andnegative signals produce anincrease in said current, and means operablein synchronism with incoming signals for periodically short-circuiting aportion of the resistance included in the input circuit of said gasflledtube.

9. In a signaling system, a signaling circuit terminated with a vacuumtube amplier having a divided output circuit, a resistance in eachbranch of said output circuit through which a portion of the platecurrent flows, a grid-com trolled, gas-filled tube associated with eachbranch of said output circuit and having its input circuit connectedacross at least a portion of said resistance, whereby the plate currentof said amplifier normally maintains the grid of said gaslled tubenegative with respect to its cathode, a pair of telegraph printers, oneassociated with each gas-lled tube, the plate circuit of each tube beingcompleted ythrough the selecting magnets of its corresponding printerthrough a pair of plate rings provided with a rotating brush, a pair ofpick-up rings having a rotating brush operating in synchronism with thebrushes of said plate rings, and circuit cohnections'between theresistance elements in said output circuit and said pick-up rings foralternately short-circuiting a portion of the resistance elementsincluded in the input circuit of said gas-filled tubes in synchronismwith incoming signals.

10. In a signaling system, a signaling circuit, a gaseous conductiontube, means for converting signals of different polarities, receivedover said circuit, into signals of varying magnitude of current, meansfor producing discharges through said tube, selectively in accordancewith the magnitude of said current, and current responsive means in theoutput circuit of said tube.

11. In a signaling system, a source of telegraph signals of varyingmagnitude of current, a gaseous conduction tube, means for producingdischarges through said tube selectively, in accordance with themagnitude of said current and current responsive means in the outputcircuit of said tube.

12. In a telegraph system, a source of telegraph signals comprisingpositive, negative and zero selecting conditions, a gaseous conductiontube and means responsive to said selecting conditions for controllingthe operation of said tube, whereby discharges will be produced thereinin accordance with said signal conditions.

13. In a telegraph system, a source of telegraph signals comprisingpositive, negative and zero selecting conditions, a gaseous conductiontube and means responsive to said selecting conditions for producing adischarge in said tube when signals of one polarity are received, forpreventing a discharge from occurring therein when signals of the otherpolarity are received,

and for starting or preventing the occurrence of a discharge thereinwhen signals of zero polarity are received, depending upon the precedingsig'- nal conditions. l

14. In a telegraph system, a source of telegraph signals, a gaseousconduction tube having a control electrode, means for applying apotential to said control electrode in accordance with said telegraphsignals and means for varying said applied potential during apredetermined portion of each signal impulse, whereby to control thestarting of a discharge through said tube, and currentv control means inthe output circuit of said tube.

15. In a telegraph system, a source of telegraph signals, a gaseousconduction tube having a control electrode, means for applying apotential to said control electrode in accordance with said telegraphsignals and a distributor operating in synchronism withsaid signals forvarying said applied potential during a predetermined portion of eachsignal impulse, whereby to control the starting of a discharge throughsaid tube, and current control means in the output circuit of said tube.

16.l In a telegraph system, a source of signal impulses, a pair ofgaseous conduction tubes having starting electrodes, means for applyingpredetermined potentials to the starting electrodes of both of saidtubes in accordance with every signal' impulse received and local meansfor selectively varying the potential applied to one of said tubes,whereby said selective tube only responds to said signal impulse.

1'7. In a telegraph system, a source of signal impulses, a pair ofgaseous conduction tubes having starting electrodes, means for applyingpredetermined potentials to the starting electrodes of both of saidtubes in accordance with every signal impulse received and local meansoperatin g in synchronism with said impulses for varying the potentialapplied to said tubes alternately, whereby said tubes respondalternately to said signal impulses.

18. In a telegraph system, a source of signal impulses, a pair ofgaseous conduction tubes having starting electrodes, meansfor applyingpredetermined potentialsv to the starting electrodes of both of saidtubes in accordance with every signal impulse received, local meansoperating in synchronism with said impulses for varying the potentialapplied to said tubes alternately, whereby said tubes respondalternately to said signal impulses, and a separate recorder in theoutput circuit of each of said tubes.

19. In a telegraphsystem, a source of signals of varying magnitudes, aresistance in circuit with said source of signals, a gaseous conductiontube having a cathode and a control electrode connected across saidresistance, whereby the drop in potential thereacross due to saidsignals, applies a predetermined bias to said control electrode andmeans for periodically shunting at least a portion of said resistance toalter said bias, whereby to control the starting of said tube.

' ALBERT W. BREYFOGEL.

